In recent years, recordable optical disk drive apparatuses such as CD-R drive apparatus have been put into practical use, and further study has been made with the aim of achieving further increase in the storage capacity and recording speed. Recordable optical disk media includes write-once optical disks using dye media, rewritable disks using magneto-optical media, phase-change media, or the like.
Typical optical disk recording apparatus uses a semiconductor laser as a light source, and emits on a record medium the laser light that is pulse-modulated in response to record information, thereby forming record marks. In doing so, the state of the formed record mark changes in response to the power of the recording laser light, so that there is a need to know a recording power that is suitable to the characteristics of the recording medium. To this end, conventionally, trial write is performed with respect to a predetermined area (PCA: power calibration area) as preparation for the start of recording while the recording power is changed. After the trial write, the area that produces the reproduced signal having the most satisfactory quality is identified, and the power that was used to record this area is identified as the optimum recording power. This method is known as an OPC (optimum power contol) method. During the actual recording of data, the optimum recording power identified in this manner is maintained while recording.
As a recording method used for optical disks such as CD and DVD, a mark edge recording method is employed in which the length of marks suitable for high-density recording carries information. In order to reproduce data correctly, there is a need for accurate control of mark shape and edge position. Further, for the purpose of organizing the mark shape evenly regardless of the length of the marks, a multi-pulse recording method is widely used that forms recording marks by use of pulse trains that are divided into a plurality of recording pulses. This method forms a long mark evenly by forming and connecting marks through the repetition of heating and cooling cycles. Such method is also employed in the write-once dye-type media.